Judith Collins is slamming James Shaw as willing to play politics with his own Government.

It's been reported Shaw refused to back other infrastructure projects - unless Taranaki's Green School was included.

Shaw's previously called out New Zealand First for being a handbrake on progress - and National leader Collins says this is rank hypocrisy.

"I thought he was going to resign yesterday after he called his press conference. I can't believe he put himself in a position where he was holding up all that work."

Finance Minister Grant Robertson says he wouldn't use the term hypocrisy.

"I don't use that word. What I know is that Mr Shaw advocated very strongly for this project."

In the House for the last time before October's election, Collins put the heat on Robertson over the funding.

But Robertson came back firing.

"A coalition government is a little like a marriage. I've known Minister Shaw for not quite 41 years, and I respect him, but I can't control everything he says or does." 

Collins' husband of 41 years has been criticised this week for sharing political memes on social media.

The Prime Minister was also grilled over why she didn't proactively speak out about incorrect information telling South and West Auckland people to get a Covid test.

Collins says it took media questions before Jacinda Ardern admitted it was an error.

Ardern insists she always planned to correct the information.

"We are here to be accountable for our Covid response, we never shy away from that duty."